168 Illinois State Lahoratory of Natural History. 



Food like that of the preceding species, the only recogniz- 

 able objects in the alimentary canals being in this case dia- 

 toms. 



The species is abundant in Cedar Creek, and was found 

 also in Ballard Slough. 



Hydrop]iiUda\ larva (1). 



A small larva with depressed and rather stout body, with a 

 median brown band on the head and a pair of obscure dusky 

 longitudinal stripes on the abdomen above. Pale below. Sides 

 of thorax and abdomen tuberculate. The mandibles are unlike 

 any others we have seen. They are rather long, sickle-shaped, 

 and bear at about the middle of their inner edge a strong tooth 

 with bicuspid apex, minute denticles on its anterior edge, and 

 one or two small teeth at its base. The largest example taken 

 is a trifle more than a half inch long. 



Locality, Cedar Creek. 



Hydrophilidcf^, larva (2). 



A small larva about .25 inch long, common in Cedar Creek, 

 is evidently the young of one of the above species of Berosus. 

 The body is widest at the middle and tapers pretty uniformly 

 to the extremities. Head small; ocelli superior; clypeus den- 

 ticulate. Basal segment of maxillae unusually long and strong. 

 Segments of body coarsely wrinkled, the seven anterior divisions 

 of the abdomen, each with a pair of long, naked respiratory 

 filaments. Terminal segment nipple-shaped; no caudal append- 

 ages. Young examples are transparent in life, but grow more 

 opaque when older. 



Family Staph ylinid.^. (Rove Beetles.) 



Small species of this family of beetles were always com- 

 mon in the mud and sand at the edges of sloughs, and many 

 were noticed floating and struggling on the surface in the latter 

 part of August, after the water had risen suddenly. 



Family Parnidje. 



These small beetles creep about or burrow in the mud un- 

 der water. From the structure of the jaws they have been 



